# Modulating quantum Fisher information of qubit in dissipative cavity by coupling strength

## TL;DR

This paper investigates how the atom-cavity and cavity-reservoir couplings influence the quantum Fisher information of a qubit in a dissipative cavity, revealing conditions that enhance parameter estimation accuracy.

## Contribution

It provides a detailed analysis of the impact of coupling strengths on QFI dynamics using non-Markovian master equations, offering insights for optimizing quantum measurement precision.

## Key findings

- Stronger atom-cavity coupling leads to faster QFI oscillations and stabilization.
- Weaker cavity-reservoir coupling enhances non-Markovian effects, slowing QFI decay.
- Optimal parameters can improve the accuracy of quantum parameter estimation.

## Abstract

By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum Fisher information (QFI) of an atom qubit system in a dissipation cavity. We obtain the formulae of QFI for two different initial states and analyze the effect of the atom-cavity coupling and the cavity-reservoir coupling on the QFI. The results show that the dynamic behavior of the QFI is obviously dependent on the initial atomic states, the atom-cavity coupling and the cavity-reservoir coupling. The stronger the atom-cavity coupling, the quicker the QFI oscillates and the slower the QFI reduces. Especially, the QFI will tend to a stable value not zero if the atom-cavity coupling is large enough. On the other hand, the smaller the cavity-reservoir coupling, the stronger the non-Markovian effect, the slower the QFI decay. In other words, choosing the best parameter can improve the accuracy of parameter estimation. In addition, the physical explanation of the dynamic behavior of the QFI is given by means of the QFI flow.